Relationship between glycosylated hemoglobin and vitamin B12 deficiency anemia

OBJECTIVE: Previous studies showed that vitamin B12 deficiency anemia causes a false increase in glycosylated hemoglobin (HbA1c) and that HbA1c decreases with B12 treatment. However, no study has been conducted on how much an increase in hemoglobin (Hgb) level causes a decrease in HbA1c level after treatment.
METHODS: The study included 37 patients who were not diagnosed with diabetes, did not use anti-diabetic drugs, were pre-diabetic according to HbA1c level, and were diagnosed with vitamin B12 deficiency anemia in the patient group and 40 healthy volunteers of similar age and gender characteristics in the control group. The patient group was given 1 mg/day of cyanocobalamin (vitamin B12) orally for 3 months. Patients’ Hgb, mean corpuscular volume, fasting plasma glucose, HbA1c, and vitamin B12 values were compared at the beginning and at the end of the 3rd month.
RESULTS: In the patient group, it was determined that 0.94 mg/dL increase in Hgb after vitamin B12 treatment caused a 0.24 decrease in HbA1c (%). The initial HbA1c of the patient group was 6.01±0.20 and the 3rd-month HbA1c was 5.77±0.33; the initial and 3rd-month Hgb values were 11.31±0.28 and 12.26±0.33, respectively; the initial and 3rd-month vitamin B12 (ng/L) levels were 112.43±7.18 and 408.48±119.61, respectively; and there was a significant difference between the initial and 3rd-month values (p<0.001, p<0.001, p<0.001, respectively). Moreover, 35% of the patients in the patient group had no diagnosis of prediabetes according to the HbA1c level at the end of the 3rd month.
CONCLUSION: Elimination of vitamin B12 deficiency anemia before making a diagnosis or treatment decision according to HbA1c level will prevent patients from misdiagnosis of diabetes and unnecessary treatment changes in diabetic patients.

Glikolize Hemoglobin ve Vitamin B12 Eksikliði Anemisi Arasýndaki Ýliþki

Giriþ: Vit B12 eksikliði anemisinin glikolize hemoglobin (HBA1c) de yalancý yüksekliðine neden olduðu ve B12 tedavisi ile HBA1c’ nin düþtüðü yapýlan çalýþmalar ile gösterilmiþtir. Ancak tedavi sonrasý hemoglobin (Hgb) düzeyindeki artýþýn ne kadarlýk HbA1c düþmesine neden olduðu ile ilgili bir çalýþma yoktur. Bu çalýþmada megaloblastik anemili hastalarda vitamin B12 tedavisinin HbA1c üzerinde etkisinin olup olmadýðý araþtýrýlmýþtýr.
Materyal-Metod: Çalýþmaya diyabet tanýsý olmayan, anti-diyabetik ilaç kullanmayan, HBA1c deðerine göre prediyabetik olan ve vitamin B12 eksikliði anemisi tanýlý 37 hasta ile kontrol grubu olarak yaþ ve cinsiyet uyumlu 40 saðlýklý gönüllü alýndý. Hasta grubuna üç ay süresince oral 1 mg/gün siyanokobalamin (B12 vitamini) verildi. Hastalarýn Hgb, mean corpuscular volum (MCV), açlýk plazma glukozu (FPG), HbA1c, vitamin B12 ve vücut kitle indeksi (BMI) deðerleri baþlangýçta ve 3. ay sonunda karþýlaþtýrýldý.
Sonuçlar: Hasta grubunda vitamin B12 tedavisinden sonra Hgb de 0,94 mg/dL artýþýn HBA1c de (%) 0,24 azalmaya neden olduðu saptandý. Hasta grubu baþlangýç HbA1c (%) 6.01 ± 0.20 iken, 3. ay HbA1c 5.77 ± 0.33, baþlangýç Hgb 11.31 ± 0.28, 3. ay Hgb 12.26 ± 0.33 baþlangýç vitamin B12 (ng/L) 112.43 ± 7.18, 3. ay vitamin B12 (ng/L) 408.48 ± 119.61 idi ve aralarýnda anlamlý bir farklýlýk vardý (sýrasýyla p<0.001, p<0.001, p<0.001). Ayrýca çalýþma grubundaki hastalarýn %35’ inin 3. ay sonunda HbA1c deðerine göre prediyabet tanýsýndan çýktýðý saptandý.
Sonuç: Anemi derinleþtikçe HBA1c’nin taný ve tedavideki güvenilirliðini azalmaktadýr. HbA1c düzeyine göre taný veya tedavi kararý verilmeden önce vitamin B12 eksikliði anemisinin düzeltilmesi, hastalarýn yanlýþ diyabet tanýsý almasýný ve diyabetik hastalardaki gereksiz tedavi deðiþikliklerini engelleyecektir. (NCI-2022-4-8/R1)